From: Dan Williams <dan.j.williams@intel.com>
Date: Wed, 6 Nov 2019 17:43:21 -0800
Subject: arm/efi: EFI soft reservation to memblock
Patch-mainline: v5.5-rc1
Git-commit: 16993c0f0a43213e23666ea40e9163887f593ac7
References: jsc#SLE-16407

UEFI 2.8 defines an EFI_MEMORY_SP attribute bit to augment the
interpretation of the EFI Memory Types as "reserved for a specific
purpose".

The proposed Linux behavior for specific purpose memory is that it is
reserved for direct-access (device-dax) by default and not available for
any kernel usage, not even as an OOM fallback.  Later, through udev
scripts or another init mechanism, these device-dax claimed ranges can
be reconfigured and hot-added to the available System-RAM with a unique
node identifier. This device-dax management scheme implements "soft" in
the "soft reserved" designation by allowing some or all of the
reservation to be recovered as typical memory. This policy can be
disabled at compile-time with CONFIG_EFI_SOFT_RESERVE=n, or runtime with
efi=nosoftreserve.

For this patch, update the ARM paths that consider
EFI_CONVENTIONAL_MEMORY to optionally take the EFI_MEMORY_SP attribute
into account as a reservation indicator. Publish the soft reservation as
IORES_DESC_SOFT_RESERVED memory, similar to x86.

(Based on an original patch by Ard)

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
 arch/arm64/mm/mmu.c                       |    2 ++
 drivers/firmware/efi/arm-init.c           |    9 +++++++++
 drivers/firmware/efi/arm-runtime.c        |   24 ++++++++++++++++++++++++
 drivers/firmware/efi/libstub/arm32-stub.c |    5 +++++
 drivers/firmware/efi/libstub/random.c     |    4 ++++
 5 files changed, 44 insertions(+)

--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1058,6 +1058,8 @@ int arch_add_memory(int nid, u64 start,
 	__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
 			     size, PAGE_KERNEL, __pgd_pgtable_alloc, flags);
 
+	memblock_clear_nomap(start, size);
+
 	return __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
 			   restrictions);
 }
--- a/drivers/firmware/efi/arm-init.c
+++ b/drivers/firmware/efi/arm-init.c
@@ -164,6 +164,15 @@ static __init int is_usable_memory(efi_m
 	case EFI_CONVENTIONAL_MEMORY:
 	case EFI_PERSISTENT_MEMORY:
 		/*
+		 * Special purpose memory is 'soft reserved', which means it
+		 * is set aside initially, but can be hotplugged back in or
+		 * be assigned to the dax driver after boot.
+		 */
+		if (efi_soft_reserve_enabled() &&
+		    (md->attribute & EFI_MEMORY_SP))
+			return false;
+
+		/*
 		 * According to the spec, these regions are no longer reserved
 		 * after calling ExitBootServices(). However, we can only use
 		 * them as System RAM if they can be mapped writeback cacheable.
--- a/drivers/firmware/efi/arm-runtime.c
+++ b/drivers/firmware/efi/arm-runtime.c
@@ -121,6 +121,30 @@ static int __init arm_enable_runtime_ser
 		return 0;
 	}
 
+	if (efi_soft_reserve_enabled()) {
+		efi_memory_desc_t *md;
+
+		for_each_efi_memory_desc(md) {
+			int md_size = md->num_pages << EFI_PAGE_SHIFT;
+			struct resource *res;
+
+			if (!(md->attribute & EFI_MEMORY_SP))
+				continue;
+
+			res = kzalloc(sizeof(*res), GFP_KERNEL);
+			if (WARN_ON(!res))
+				break;
+
+			res->start	= md->phys_addr;
+			res->end	= md->phys_addr + md_size - 1;
+			res->name	= "Soft Reserved";
+			res->flags	= IORESOURCE_MEM;
+			res->desc	= IORES_DESC_SOFT_RESERVED;
+
+			insert_resource(&iomem_resource, res);
+		}
+	}
+
 	if (efi_runtime_disabled()) {
 		pr_info("EFI runtime services will be disabled.\n");
 		return 0;
--- a/drivers/firmware/efi/libstub/arm32-stub.c
+++ b/drivers/firmware/efi/libstub/arm32-stub.c
@@ -146,6 +146,11 @@ static efi_status_t reserve_kernel_base(
 			continue;
 
 		case EFI_CONVENTIONAL_MEMORY:
+			/* Skip soft reserved conventional memory */
+			if (efi_soft_reserve_enabled() &&
+			    (desc->attribute & EFI_MEMORY_SP))
+				continue;
+
 			/*
 			 * Reserve the intersection between this entry and the
 			 * region.
--- a/drivers/firmware/efi/libstub/random.c
+++ b/drivers/firmware/efi/libstub/random.c
@@ -58,6 +58,10 @@ static unsigned long get_entry_num_slots
 	if (md->type != EFI_CONVENTIONAL_MEMORY)
 		return 0;
 
+	if (efi_soft_reserve_enabled() &&
+	    (md->attribute & EFI_MEMORY_SP))
+		return 0;
+
 	region_end = min((u64)ULONG_MAX, md->phys_addr + md->num_pages*EFI_PAGE_SIZE - 1);
 
 	first_slot = round_up(md->phys_addr, align);